1. Field of the Invention
The invention relates to a process for producing an electronic component in which electronic parts are located in a plastic housing, such as a Hall sensor.
2. Description of Related Art
Electronic components have been produced to date by potting or tightly embedding their electronic parts in a plastic housing because direct extrusion coating of electronic parts is not possible due to the thermal stresses in an extrusion coating process. These thermal stresses can result in possible damage of the electronic components due to the pressure load which occurs thereby. This means that finish-extrusion coating, for example, with thermoplastics or duroplastics, can destroy the electronic parts and can damage them because of the overly high pressure and at overly high temperature. On the other hand, potting with PU or epoxy resins is undesirable since such potting becomes hard and inflexible after curing.
To protect electronic parts against the damaging effects of an overly high pressure or an overly high temperature, they must be protected with an additional cover or a cap or by a potting compound in order to keep the injection compound away. This results in the fact that additional parts such as housing, cover, etc. must be used at added material and manufacturing costs.
In addition, potting of electronic parts, for example, with PU potting, requires a high cycle time for setting and is impractical for use in series production.
Other problems in the conventional production processes lie in the lack of fixing of the protective cover or the protective cap, formation of cavities with air inclusions, problems with different coefficients of thermal expansion of the materials during embedding with hard potting compounds and in the danger of cracks of parts during temperature cycles.
These difficulties become apparent in the conventional production processes as high time consumption and costs.
The primary object of the present invention is to devise an improved process for producing an electronic component in which electronic parts are located in a plastic housing that is efficient and cost effective.
This primary object is achieved the process for producing an electronic component in accordance with the present invention where the electronic parts are located in a hot-melt adhesive mass and afterwards, are finish-extrusion coated to form the housing.
In the process in accordance with the present invention, reliable embedding and fixing of the electronic parts in the hot-melt adhesive mass is possible such that the housing can then be formed with a conventional extrusion coating process and the electronic component thus acquires its final form.
Preferably, the electronic parts are embedded in the hot-melt adhesive mass or are extrusion coated with the hot-melt adhesive mass.
In particular, if similar materials are used for the mount of the electronic parts, the hot-melt adhesive as well as the housing, it is possible to equalize the coefficients of thermal expansion of these materials to such an extent that no problems arise in respect to thermal expansion.
In one preferred embodiment, these materials are polyamide materials.
This and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments when viewed in conjunction with the attached drawings.